More bus driver strikes are likely in Auckland after more than 500 drivers today voted to reject the latest pay offer from NZ Bus.

There was hope last week that the unions and NZ Bus had come to an agreement and drivers were meeting today to lock in the collective contract.

However Karl Andersen, spokesman for the combined bus unions, said the workers believed they were still being undervalued by the company and deserved to be paid better.

"Bus drivers are working split shifts and long hours and want to have sufficient wages at the end of the working week to have a decent life," he said.

"While the offer put to workers today was an improvement from the company, it did not meet union members' expectations and needs to improve."

Andersen said drivers were not earning enough to pay bills and give their families a decent standard of living, and the delayed implementation of pay increases offered by the company prolonged this hardship.

"Drivers are also concerned about changes to their rosters that the company has introduced in the last couple of weeks."

The unions have told NZ Bus they have rejected the offer and said they are keen to get back into negotiations. Members also voted to strike in a bid to get a better agreement.

"Negotiating with this group is a bit like Groundhog Day, it's hugely frustrating - we worked very hard to see their point of view, worked constructively with them and reached an agreement which they endorsed and then they vote it down," he said.